Kidney stones form in the kidney and usually do not cause any symptoms while residing in the kidney. A ureteral stone is a kidney stone that has passed from the kidney into the ureter. The ureter is a narrow tube that connects the kidney to the bladder. The function of the ureter is to drain urine from the kidney to the bladder. When a kidney stone passes into the ureter, an obstruction or blockage can occur, causing the kidney to swell. This obstruction can lead to severe back or flank pain and nausea and vomiting. Small stones (less than 5 mm) in diameter are usually able to pass spontaneously without any surgical intervention. The process of passing a stone may take hours, days, or even weeks. Stones larger than 5 mm in size are much less likely to spontaneously pass, so your urologist is more likely to suggest a surgical intervention to treat the stone.
For more information go to Kidney Stones.